matchers.go

/*
Copyright 2021 Gravitational, Inc.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package services

import (
	"github.com/gravitational/trace"
	"github.com/sirupsen/logrus"

	"github.com/zmb3/teleport/api/types"
)

// ResourceMatcher matches cluster resources.
type ResourceMatcher struct {
	// Labels match resource labels.
	Labels types.Labels
}

// AWSSSM provides options to use when executing SSM documents
type AWSSSM struct {
	// DocumentName is the name of the document to use when executing an
	// SSM command
	DocumentName string
}

// InstallerParams are passed to the AWS SSM document
type InstallerParams struct {
	// JoinMethod is the method to use when joining the cluster
	JoinMethod types.JoinMethod
	// JoinToken is the token to use when joining the cluster
	JoinToken string
	// ScriptName is the name of the teleport script for the EC2
	// instance to execute
	ScriptName string
}

// AWSMatcher matches AWS databases.
type AWSMatcher struct {
	// Types are AWS database types to match, "rds" or "redshift".
	Types []string
	// Regions are AWS regions to query for databases.
	Regions []string
	// Tags are AWS tags to match.
	Tags types.Labels
	// Params are passed to AWS when executing the SSM document
	Params InstallerParams
	// SSM provides options to use when sending a document command to
	// an EC2 node
	SSM *AWSSSM
}

// AzureMatcher matches Azure databases.
type AzureMatcher struct {
	// Subscriptions are Azure subscriptions to query for resources.
	Subscriptions []string
	// ResourceGroups are Azure resource groups to query for resources.
	ResourceGroups []string
	// Types are Azure resource types to match, for example "mysql" or "postgres".
	Types []string
	// Regions are Azure regions to query for databases.
	Regions []string
	// ResourceTags are Azure tags to match.
	ResourceTags types.Labels
}

// GCPMatcher matches GCP resources.
type GCPMatcher struct {
	// Types are GKE resource types to match: "gke".
	Types []string `yaml:"types,omitempty"`
	// Locations are GCP locations to search resources for.
	Locations []string `yaml:"locations,omitempty"`
	// Tags are GCP labels to match.
	Tags types.Labels `yaml:"tags,omitempty"`
	// ProjectIDs are the GCP project IDs where the resources are deployed.
	ProjectIDs []string `yaml:"project_ids,omitempty"`
}

// MatchResourceLabels returns true if any of the provided selectors matches the provided database.
func MatchResourceLabels(matchers []ResourceMatcher, resource types.ResourceWithLabels) bool {
	for _, matcher := range matchers {
		if len(matcher.Labels) == 0 {
			return false
		}
		match, _, err := MatchLabels(matcher.Labels, resource.GetAllLabels())
		if err != nil {
			logrus.WithError(err).Errorf("Failed to match labels %v: %v.",
				matcher.Labels, resource)
			return false
		}
		if match {
			return true
		}
	}
	return false
}

// ResourceSeenKey is used as a key for a map that keeps track
// of unique resource names and address. Currently "addr"
// only applies to resource Application.
type ResourceSeenKey struct{ name, addr string }

// MatchResourceByFilters returns true if all filter values given matched against the resource.
//
// If no filters were provided, we will treat that as a match.
//
// If a `seenMap` is provided, this will be treated as a request to filter out duplicate matches.
// The map will be modified in place as it adds new keys. Seen keys will return match as false.
//
// Resource KubeService is handled differently b/c of its 1-N relationhip with service-clusters,
// it filters out the non-matched clusters on the kube service and the kube service
// is modified in place with only the matched clusters. Deduplication for resource `KubeService`
// is not provided but is provided for kind `KubernetesCluster`.
func MatchResourceByFilters(resource types.ResourceWithLabels, filter MatchResourceFilter, seenMap map[ResourceSeenKey]struct{}) (bool, error) {
	var specResource types.ResourceWithLabels

	// We assume when filtering for services like KubeService, AppServer, and DatabaseServer
	// the user is wanting to filter the contained resource ie. KubeClusters, Application, and Database.
	resourceKey := ResourceSeenKey{}
	switch filter.ResourceKind {
	case types.KindNode, types.KindWindowsDesktop, types.KindWindowsDesktopService, types.KindKubernetesCluster:
		specResource = resource
		resourceKey.name = specResource.GetName()

	case types.KindKubeService, types.KindKubeServer:
		if seenMap != nil {
			return false, trace.BadParameter("checking for duplicate matches for resource kind %q is not supported", filter.ResourceKind)
		}
		return matchAndFilterKubeClusters(resource, filter)

	case types.KindAppServer:
		server, ok := resource.(types.AppServer)
		if !ok {
			return false, trace.BadParameter("expected types.AppServer, got %T", resource)
		}
		specResource = server.GetApp()
		app := server.GetApp()
		resourceKey.name = app.GetName()
		resourceKey.addr = app.GetPublicAddr()

	case types.KindDatabaseServer:
		server, ok := resource.(types.DatabaseServer)
		if !ok {
			return false, trace.BadParameter("expected types.DatabaseServer, got %T", resource)
		}
		specResource = server.GetDatabase()
		resourceKey.name = specResource.GetName()

	default:
		return false, trace.NotImplemented("filtering for resource kind %q not supported", filter.ResourceKind)
	}

	var match bool

	if len(filter.Labels) == 0 && len(filter.SearchKeywords) == 0 && filter.PredicateExpression == "" {
		match = true
	}

	if !match {
		var err error
		match, err = matchResourceByFilters(specResource, filter)
		if err != nil {
			return false, trace.Wrap(err)
		}
	}

	// Deduplicate matches.
	if match && seenMap != nil {
		if _, exists := seenMap[resourceKey]; exists {
			return false, nil
		}
		seenMap[resourceKey] = struct{}{}
	}

	return match, nil
}

func matchResourceByFilters(resource types.ResourceWithLabels, filter MatchResourceFilter) (bool, error) {
	if filter.PredicateExpression != "" {
		parser, err := NewResourceParser(resource)
		if err != nil {
			return false, trace.Wrap(err)
		}

		switch match, err := parser.EvalBoolPredicate(filter.PredicateExpression); {
		case err != nil:
			return false, trace.BadParameter("failed to parse predicate expression: %s", err.Error())
		case !match:
			return false, nil
		}
	}

	if !types.MatchLabels(resource, filter.Labels) {
		return false, nil
	}

	if !resource.MatchSearch(filter.SearchKeywords) {
		return false, nil
	}

	return true, nil
}

// matchAndFilterKubeClusters is similar to MatchResourceByFilters, but does two things in addition:
//  1. handles kube service having a 1-N relationship (service-clusters)
//     so each kube cluster goes through the filters
//  2. filters out the non-matched clusters on the kube service and the kube service is
//     modified in place with only the matched clusters
//  3. only returns true if the service contained any matched cluster
func matchAndFilterKubeClusters(resource types.ResourceWithLabels, filter MatchResourceFilter) (bool, error) {
	if len(filter.Labels) == 0 && len(filter.SearchKeywords) == 0 && filter.PredicateExpression == "" {
		return true, nil
	}

	switch server := resource.(type) {
	case types.Server:
		return matchAndFilterKubeClustersLegacy(server, filter)
	case types.KubeServer:
		kubeCluster := server.GetCluster()
		if kubeCluster == nil {
			return false, nil
		}
		match, err := matchResourceByFilters(kubeCluster, filter)
		return match, trace.Wrap(err)
	default:
		return false, trace.BadParameter("unexpected kube server of type %T", resource)
	}

}

// matchAndFilterKubeClustersLegacy is used by matchAndFilterKubeClusters to filter kube clusters that are stil living in old kube services
// REMOVE in 13.0
func matchAndFilterKubeClustersLegacy(server types.Server, filter MatchResourceFilter) (bool, error) {
	kubeClusters := server.GetKubernetesClusters()

	// Apply filter to each kube cluster.
	filtered := make([]*types.KubernetesCluster, 0, len(kubeClusters))
	for _, kube := range kubeClusters {
		kubeResource, err := types.NewKubernetesClusterV3FromLegacyCluster(server.GetNamespace(), kube)
		if err != nil {
			return false, trace.Wrap(err)
		}

		match, err := matchResourceByFilters(kubeResource, filter)
		if err != nil {
			return false, trace.Wrap(err)
		}
		if match {
			filtered = append(filtered, kube)
		}
	}

	// Update in place with the filtered clusters.
	server.SetKubernetesClusters(filtered)

	// Length of 0 means this service does not contain any matches.
	return len(filtered) > 0, nil
}

// MatchResourceFilter holds the filter values to match against a resource.
type MatchResourceFilter struct {
	// ResourceKind is the resource kind and is used to fine tune the filtering.
	ResourceKind string
	// Labels are the labels to match.
	Labels map[string]string
	// SearchKeywords is a list of search keywords to match.
	SearchKeywords []string
	// PredicateExpression holds boolean conditions that must be matched.
	PredicateExpression string
}

const (
	// AWSMatcherRDS is the AWS matcher type for RDS databases.
	AWSMatcherRDS = "rds"
	// AWSMatcherRDSProxy is the AWS matcher type for RDS Proxy databases.
	AWSMatcherRDSProxy = "rdsproxy"
	// AWSMatcherRedshift is the AWS matcher type for Redshift databases.
	AWSMatcherRedshift = "redshift"
	// AWSMatcherElastiCache is the AWS matcher type for ElastiCache databases.
	AWSMatcherElastiCache = "elasticache"
	// AWSMatcherMemoryDB is the AWS matcher type for MemoryDB databases.
	AWSMatcherMemoryDB = "memorydb"
	// AWSMatcherEC2 is the AWS matcher type for EC2 instances.
	AWSMatcherEC2 = "ec2"
	// AzureMatcherMySQL is the Azure matcher type for Azure MySQL databases.
	AzureMatcherMySQL = "mysql"
	// AzureMatcherPostgres is the Azure matcher type for Azure Postgres databases.
	AzureMatcherPostgres = "postgres"
	// AzureMatcherRedis is the Azure matcher type for Azure Cache for Redis databases.
	AzureMatcherRedis = "redis"
)